It is heretofore known to use copper wirings in a layer to which a bonding wire is connected in order to achieve low resistance.
For example, Patent Literature 1 (Japanese Patent Application Publication No. 2001-319946) discloses a semiconductor device that includes a copper electrode formed on an dielectric substance, a barrier layer made of Ni or the like formed on the copper electrode, and an outermost layer made of Au or the like formed on the barrier layer, and a wire is connected to the outermost layer.
In a process for manufacturing this semiconductor device, both the barrier layer and the outermost layer covering the copper electrode are formed by first forming a seed metal on the surface of the copper electrode and then allowing each material to grow from this seed metal according to electroless plating.